Yeltsin also ordered the disbanding of a 5,000-member security force controlled by parliament Speaker Ruslan Khasbulatov. The step was prompted by parliament's attempt on Tuesday to take over the Izvestia newspaper.

Both of Yeltsin's actions underscored the president's growing concern over challenges to his personal power and the future of market reforms.

The ban is "a trial balloon to see how the people would react to the idea of presidential rule," said Ilya Konstantinov, an NSF leader. "The ban violates the Constitution, and we don't recognize it."

NSF members say Yeltsin is undermining his position by outlawing their organization. "Draconian measures taken against the Front will only serve to increase the number of our supporters and to strengthen our will," Mr. Konstantinov said.

The president, as the "guarantor of democracy and basic freedoms," banned the NSF because it threatens stability, Yeltsin's press service said.